Question

As I have read, it is not easy for JavaScript to modify files on client PC. I am working on a web based file manager and would need to know the following:

• Can JavaScript list files and folder structure on a client PC?
• Can JavaScript list files and folder structure on a server?

If your answer is no, that Java Scipt can not list files and folders say on client’s or server’s C:\ drive, than would CGI script be the only solution?

Answer 1

Browser JS reading client PC’s files: Depends

For a security reason, you can’t access the files on the user’s PC without the user’s consent.

That’s why the FileReader API is created around the file input box <input type="file"> and a drag-n-drop area since the whole idea is to "access the file with user’s consent". Without the user intentionally putting the file for access, you can’t access it at all.

Server-side JS reading own server’s files: Yes

As for server, if you meant access the server using server-JS (NodeJS or Rhino), yes you can (How else would it serve webpages anyway?).

Browser JS reading own server’s files: Depends

Accessing the server from the browser using JS works if you have an API to read files from it.

Browser JS reading other server’s files: Yes, with a catch

To access other server’s files without some API, you could resort to creating a web scraper or a web-spider that runs server-side (since browser can’t cross domains due to the same origin policy) and have an API exposed to your browser.

However:

• you can’t crawl to all files as some may be restricted from outside access.
• the public appearance of the structure could be different from the internal structure, especially if the site uses segmented url scheme
• sites using query strings to generate pages cannot be crawled easily due to the number of permutations it could make, thus some pages might be unreacheable.